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Pinaceae FAMILY Least Concern

Tsuga mertensiana

Tsuga mertensiana

Edibility
2/5
Medicinal
2/5

Safety & Hazards

None known

Cultivation Details

HabitEvergreen Tree
GrowthMedium

Tsuga mertensiana is a subalpine species growing in areas of western N. America that have a cool to cold maritime climate that includes mild to cold winters, a short, warm to cool growing season and moderate to high precipitation[1]. It occurs from near sea level in Alaska to elevations of 1,500 metres, and gradually ascending further south in its range so that in California it is found at 1,800 - 3, 350 metres[2]. Subspecies mertensiana is restricted to a climatic zone with high precipitation, in British Columbia it is between 2,000 - 4,000mm per year, with long, snowy winters and short, cool summers. Subspecies grandicona grows further south in a much drier climate, but there it is found primarily on high, north-facing slopes[2]. The growing season (frost-free period) ranges from 49 - 148 days[1]. An easily grown plant, it thrives best in cultivation when growing in a deep well-drained soil in the moister regions of the temperate zone, where it appreciates the higher rainfall[3]. However, it succeeds in most soils and positions, being especially good on acidic sandy soils[4]. In the wild it grows on a variety of non-calcareous acidic soils, sometimes on peat, more commonly on mor humus with a pH 3.1 - 3.9[2]. Plants are very shade tolerant when young, but need more sunlight as they grow older[4, 5]. Plants are thin and poor when grown in dry or exposed places[5]. Dislikes atmospheric pollution[6]. This is a very handsome tree, with its branches densely clothed with pale, spreading leaves and is adaptable to a wide variety of climatic conditions[3, 7] Among the range of cultivars, the 'blue' or glaucous leaf forms or selections are especially valued. High altitude provenances may be susceptible to 'late' frost, but those from more coastal northern areas should not suffer from this kind of damage as much[2]. The tree is slow growing for the first few years, averaging 30cm a year, but older trees, especially in areas with cool moist summers, are growing rapidly[8]. Trees live 400 - 500 years in the wild with specimens more than 800 years old recorded[9, 1]. They commence bearing seeds when about 20 - 30 years old, years of high production alternating with years of low production[9]. In several areas, e.g. In the Coast Mountains of British Columbia, the Olympic Mountains of Washington, and in Lassen Volcanic National Park (Cascades), this species is invading subalpine meadows and late-lying snow basins. In some areas this has been going on for 150 years or longer, in other areas it seems to have begun more recently. The warming climate is likely responsible[2]. Plants in this genus are notably resistant to honey fungus[5].

Propagation

Seed - it germinates better if given a short cold stratification[10, 11] and so is best sown in a cold frame in autumn to late winter. It can also be sown in early spring, though it might not germinate until after the next winter. If there is sufficient seed, an outdoor sowing can be made in spring[12]. Pot-grown seedlings are best potted up into individual pots once they are large enough to handle - grow them on in a cold frame and plant them out in early summer of the following year. Trees transplant well when they are up to 80cm tall, but they are best put in their final positions when they are about 30 - 45 cm or less tall, this is usually when they are about 5 - 8 years old[5]. Larger trees will check badly and hardly put on any growth for several years. This also badly affects root development and wind resistance[5]. Cite as: Temperate Plants Database, Ken Fern. temperate.theferns.info. 2026-02-21. <temperate.theferns.info/plant/Tsuga+mertensiana>

Pollinators

Wind

References

  1. [1]Silvics of North America. Agricultural Handbook No. 654. — Burns. R.M. & Honkala. B.H. · USDA Forest Service; Washington DC. · 1990 · http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm ↩︎A very comprehensice guide to about 200 species of timber trees of N. America, Hawaii and Puerto Rico. Mainly temperate species, plus a number of tropical species. It is downloadable from the Internet.
  2. [2]IUCN Red List of Threatened Species — http://www.iucnredlist.org/ ↩︎A list of plants under threat and facing possible extinction, usually with brief details of the threats and information on habitat.
  3. [3]Trees and Shrubs Hardy in Great Britain. Vol 1 - 4 and Supplement. — Bean. W. · Murray · 1981 · ISBN - ↩︎A classic with a wealth of information on the plants, but poor on pictures.
  4. [4]Conifers. — Rushforth. K. · Christopher Helm · 1987 · ISBN 0-7470-2801-X ↩︎Deals with conifers that can be grown outdoors in Britain. Good notes on cultivation and a few bits about plant uses.
  5. [5]The New RHS Dictionary of Gardening. 1992. — Huxley. A. · MacMillan Press · 1992 · ISBN 0-333-47494-5 ↩︎Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
  6. [6]Manual of the Trees of N. America. — Sargent. C. S. · Dover Publications Inc. New York. · 1965 · http://www.biodiversitylibrary.org/ · ISBN 0-486-20278-X ↩︎Two volumes, a comprehensive listing of N. American trees though a bit out of date now. Good details on habitats, some details on plant uses. Not really for the casual reader. It can be downloaded from the internet.
  7. [7]Flora of N. America — http://flora.huh.harvard.edu/fna/ ↩︎An on-line version of the flora with an excellent description of the plant including a brief mention of plant uses.
  8. [8]Conifers in the British Isles. — Mitchell. A. F. · HMSO · 1975 · ISBN 0-11-710012-9 ↩︎A bit out of date (first published in 1972), but an excellent guide to how well the various species of conifers grow in Britain giving locations of trees.
  9. [9]The Complete Trees of N. America. Field Guide and Natural History. — Elias. T. · Van Nostrand Reinhold Co. · 1980 · ISBN 0442238622 ↩︎A very good concise guide. Gives habitats, good descriptions, maps showing distribution and a few of the uses. It also includes the many shrubs that occasionally reach tree proportions.
  10. [10]Hardy Woody Plants from Seed. — McMillan-Browse. P. · Grower Books · 1985 · ISBN 0-901361-21-6 ↩︎Does not deal with many species but it is very comprehensive on those that it does cover. Not for casual reading.
  11. [11]The Reference Manual of Woody Plant Propagation. — Dirr. M. A. and Heuser. M. W. · Athens Ga. Varsity Press · 1987 · ISBN 0942375009 ↩︎A very detailed book on propagating trees. Not for the casual reader.
  12. [12]Propagation of Trees, Shrubs and Conifers. — Sheat. W. G. · MacMillan and Co · 1948 · ISBN - ↩︎A bit dated but a good book on propagation techniques with specific details for a wide range of plants.
  13. [13]Food Plants of the N. American Indians. — Yanovsky. E. · U.S. Depf of Agriculture. · ISBN - ↩︎A comprehensive but very terse guide. Not for the casual reader.
  14. [14]Discovering Wild Plants - Alaska, W. Canada and the Northwest. — Schofield. J. J. · Alaska Northwest Books; Alaska · 2003 · ISBN 0882403699 ↩︎A nice guide to some useful plants in that area.
  15. [15]Cornucopia - A Source Book of Edible Plants. — Facciola. S. · Kampong Publications · 1990 · ISBN 0-9628087-0-9 ↩︎Excellent. Contains a very wide range of conventional and unconventional food plants (including tropical) and where they can be obtained (mainly N. American nurseries but also research institutes and a lot of other nurseries from around the world.
  16. [16]The Herb Book. — Lust. J. · Bantam books · 1983 · ISBN 0-553-23827-2 ↩︎Lots of information tightly crammed into a fairly small book.
  17. [17]Native American Ethnobotany — Moerman. D. · Timber Press. Oregon. · 1998 · ISBN 0-88192-453-9 ↩︎Very comprehensive but terse guide to the native uses of plants. Excellent bibliography, fully referenced to each plant, giving a pathway to further information. Not for the casual reader.
  18. [18]Dictionary of Economic Plants. — Uphof. J. C. Th. · Weinheim · 1959 · ISBN - ↩︎An excellent and very comprehensive guide but it only gives very short descriptions of the uses without any details of how to utilize the plants. Not for the casual reader.
  19. [19]A Dictionary of Plants Used by Man. — Usher. G. · Constable · 1974 · ISBN 0094579202 ↩︎Forget the sexist title, this is one of the best books on the subject. Lists a very extensive range of useful plants from around the world with very brief details of the uses. Not for the casual reader.
  20. [20]Vegetable Gums and Resins. — Howes. F. N. · Faber · ISBN 81-88818-17-8 ↩︎A very good book dealing with the subject in a readable way.
  21. [21]Economic Botany. — Hill. A. F. · The Maple Press · 1952 · ISBN - ↩︎Not very comprehensive, but it is quite readable and goes into some detail about the plants it does cover.